Purpose

Evaluate the total carbonate buffering system in the body, acid-base balance. High results may represent respiratory acidosis with CO₂ retention, or metabolic alkalosis (eg, prolonged vomiting). Low value may indicate respiratory alkalosis as in hyperventilation or metabolic acidosis (eg, diabetes with ketoacidosis).

Evaluate electrolytes, acid-base balance, water balance. Chloride generally increases and decreases with plasma or serum sodium. Chloride is increased in dehydration, with ammonium chloride administration, with renal tubular acidosis (hyperchloremic metabolic acidosis) and with excessive infusion of normal saline. Differential diagnosis of acidemias and alkalemias. Chloride is higher in hyperparathyroidism than in some of the other causes of hypercalcemia, but a great deal of overlap exists.

Chloride is decreased with overhydration, congestive failure, syndrome of inappropriate secretion of ADH, vomiting, gastric suction, chronic respiratory acidosis, Addison disease, salt-losing nephritis, burns, metabolic alkalosis, and in some instances of diuretic therapy.